MySQL multi-table query and its group by group sort

//Multi-table query: Get the latest data before you execute a multi-table query

SELECT * from' Students ' st ' Right JOIN(  SELECT *  from 
(
SELECT *  fromGoutongWHEREgoutongs= ' asdf 'ORDER  byTimeDESC
　　) asGttGROUP  bygtt.name_idORDER  byGtt.goutong_timeDESC) GT
 on' GT '. ' name_id '=' St '. ' ID ' LIMITTen

//Sort the query by time and then group (group   by)
SELECT *  from(SELECT *  fromGoutongWHEREGoutongs='asdf' ORDER  byTimeDESC) asGttGROUP  bygtt.name_idORDER  byGtt.timeDESC

Reference: http://blog.csdn.net/shellching/article/details/8292338

With Data sheet comments
------------------------------------------------
| ID | NewsID | Comment | Thetime |
------------------------------------------------
|        1 |         1 |     AAA | 11 |
------------------------------------------------
|        2 |         1 |     BBB | 12 |
------------------------------------------------
|        3 |         2 |     CCC | 12 |

------------------------------------------------

NewSID is the news ID, there are several comments per news comment,thetime is the time to comment

Now you want to see the latest comment for each news article:

SELECT * from Comments GROUP BY NewsID obviously not.

SELECT * from Comments GROUP by NewsID ORDER BY thetime Desc is an out-of-group sort or not

There are two ways to accomplish this:

(1)
Selet Tt.id,tt.newsid,tt.comment,tt.thetime from (
Select Id,newsid,comment,thetime from comments ORDER BY thetime Desc) as TT GROUP by NewsID

(2)
Select Id,newsid,comment,thetime from comments as TT GROUP BY Id,newsid,comment,thetime have
Thetime= (select Max (thetime) from comments where Newsid=tt.newsid)

MySQL multi-table query and its group by group sort